Commit deedcb3a authored by heikki@hundin.mysql.fi's avatar heikki@hundin.mysql.fi
Browse files

btr0cur.c: 

  Remove long latch hold which happened if we scanned long an index without finding any record visible to the current consistent read
parent 6cc7c598

innobase/btr/btr0cur.c

+25 −0
Original line number Diff line number Diff line
@@ -302,6 +302,9 @@ btr_cur_search_to_nth_level( 
		rw_lock_s_unlock(&btr_search_latch);

	}



	/* Store the position of the tree latch we push to mtr so that we

	know how to release it when we have latched leaf node(s) */



	savepoint = mtr_set_savepoint(mtr);



	tree = index->tree;
@@ -506,12 +509,18 @@ btr_cur_open_at_index_side( 
	ulint		root_height;

	rec_t*		node_ptr;

	ulint		estimate;

	ulint           savepoint;



	estimate = latch_mode & BTR_ESTIMATE;

	latch_mode = latch_mode & ~BTR_ESTIMATE;

	

	tree = index->tree;

	

	/* Store the position of the tree latch we push to mtr so that we

	know how to release it when we have latched the leaf node */



	savepoint = mtr_set_savepoint(mtr);



	if (latch_mode == BTR_MODIFY_TREE) {

		mtr_x_lock(dict_tree_get_lock(tree), mtr);

	} else {
@@ -544,6 +553,22 @@ btr_cur_open_at_index_side( 
		if (height == 0) {

			btr_cur_latch_leaves(tree, page, space, page_no,

						latch_mode, cursor, mtr);



			/* In versions <= 3.23.52 we had forgotten to

			release the tree latch here. If in an index scan

			we had to scan far to find a record visible to the

			current transaction, that could starve others

			waiting for the tree latch. */

 

			if ((latch_mode != BTR_MODIFY_TREE)

			    && (latch_mode != BTR_CONT_MODIFY_TREE)) {



				/* Release the tree s-latch */



				mtr_release_s_latch_at_savepoint(

						mtr, savepoint,

						dict_tree_get_lock(tree));

			}

		}

		

		if (from_left) {